Rita Ora's outfit was too risque for 7pm, according to some BBC viewersGetty

Fans have come to the defence of pop superstar Rita Ora after her cleavage-bearing outfit provoked over 400 complaints from One Show viewers.

The BBC came under fire for allowing the singer, who was promoting the new series of the Voice alongside fellow judges Will.i.am, Tom Jones and Ricky Wilson, to flaunt her chest on the pre-watershed show.

Ora, who is the new judge on the singing competition, sat alongside her three male co-stars as outrage erupted online.

"I do not want to see her boobs hanging out on a family programme,' one viewer wrote on the BBC's Points of View message board.

In the wake of the backlash, the broadcaster issued an apology to fans, insisting that if it had screened the star before the show she would have been asked to wear something more appropriate.

"We're assessing these complaints to see if there is merit to take it further, but not every investigation is determined by the volume we receive," an spokesperson for Ofcom said.

"That wasn't the 24-year-old singer's only daring outfit of the day as she earlier appeared in a low-cut blue gown with a thigh-high split."

However, not all viewers felt the Black Widow singer's low-cut white blazer was offensive.

"All these complaints have done is raise the fact that we live in a society that still values a woman's appearance over her accomplishments," the Metro's Vicky Chandler added.

The internet storm comes just days after Ora – who has three UK number one singles and a UK number one album under her belt – claimed that it is harder to make it in music if you are a woman.

"Without pulling the female card, I think it has always been harder for females in all aspects," she told The Sun. "Whenever we have an opinion, it always seems to be taken out of proportion ... I think people take the word 'feminist' really seriously and I think people are scared to use that word.

"In this industry, all the heads of labels are men. I have always been very vocal about the women sticking together."